Adjusting device for magnetos



June 16, 1931. -J, F, MAR-rm A 1,810,367

ADJUSTING DEVICE FOR IIAGNETOS Filed Jan. 24, 1930 lll-f INVENTQRg55/7F- Muff/h QM ,4 @mw ATTORNEY Patented June 16,1931

PATENT OFFICE JOI-INF. MARTIN, or SPRINGFIELD, MASSACHUSETTS, ASSIGNORTo AMERICAN BOSCH MAGNETO CORPORATION, NEW YORK H OF SPRINGFIELD,MASSACHUSETTS, A CORPORATION OF AnJusTING DEVICE FOR. MAGNETOSApplicatrm*filed January 24, 1930.` Seria1 No. 423,228.

My invention relates to adjusting devices `for magnetos, particularlymagnetos used for ignition purposes in connection with internalcombustion engines. In the operation of sucha magneto, the spark forignition must of course be delivered at a definitepoint in the cycleofmovement of the parts. l'

If the magneto is of the bipolar type, with a rotatable armature betweenits pole pieces,

,theV armature havinga suitable number of turns of wire thereon, thespark should be delivered when the trailing edge of eachhead of thearmature is separated from the tip of the adjacent pole piece,-for avery brief instant-j-by a predetermined space of interval, technicallyknown .as the edge distance of the magneto. Whenthis edge distance? isrelativelysmall, forv example, a. little over three millimeters for anVordinary magneto, and the circuit of the generating winding on thearmature is opened by theV .circuit breaker or interrupter incorresponding position, the spark is advanced to the maximum degree; andby increasing the edgefdistance and shifting the point of actuation ofthe circuit breaker accordingly, the Spark canibe more or less'retarded.In practice, however, due to variations arisingin the manufacture of thecircuit breaker of the magneto, the'cam ring and other elements, theparts when mounted Voften fail to sustainto one another the relationsnecessary toperform accurately the function here described. Henceadjustinent after the assembling of the magneto must be permitted. Vi Anobject of the invention is to provide a simple and inexpensive device orappliance Y,which can be-readily atta'c'hedjto a magneto ment required.

and easily manipulated to afford the adjust- VAfrther'object of theinvention is to provide an adjustable device of this sort, capable ofbeing properly secured to the front of a magneto beneath the circuitbreaker or inter.-

Vruptei` thereof, and aordingV easy access when the position f of Vthedevice is to be altered. j Y

These and other objects and advantages of the invention ,are set forththe fOllowngde-i scription, ktaken withy the drawings, and while Iillustrate a preferred form of my invention, I ofcourse reserve theright to make changes in ,detailsY without exceeding ythe scopeandspiritof the invention or departing from the principle underlyingsame.

On the drawings(v i r.

Fig. 1 is a viewl in longitudinal'section` of theV rear `part of. amagneto with a circuit Y breaker, and' an adjusting device-according Vtomy invention; Fig. 2 is a front sectional view thereof, taken on theline 2-2 in'Fig. `1; Fig. 3-is a similarV View showing the positionofthe armatureanditheedge distance for an advanced spark; and Figs. 4 and5 are perspective views showing alternative forms of my adjustingdevice, -f "fl f The same numerals identify the samev arts.

The numeral 1 shows part of the. rame work or housing of a magneto,which maybe of the usual bipolar design, having permanent magnets, withlower ends shown at 2, extendingupward from the base 3 of the housing l.In the housing 1 is a rotatable armature 4, mountedbetweenthepolepiece's. This armature has'heads 6 and 7, with curved Outer faces,connected by a core 8; andon the'core between the heads ,is the winding(not shown) in which `are generated .ther voltage and current.' Atoneend the heads 6 Vand 7 are connected by aV plate 9 having a trunnionor journal 10;` and the adjacent end of the housing 1 hasan insiderecess containingI an anti-friction bearing 11 engaging the trillinion10. The opposite ends Aof the heads 6 and 7 are similarly Vconnectedtothe drive (shaft for the magneto, which is a solid spindle that can beunited by a Suitable coupling to the member that furnishes thelpower Vtooperate thearmature 4.

The end of the housing lsu'pporting thel journal 10 has an exteriorprojectionl2Y overy I which fits snugly a rimmed cap 13. This cap andprojection mount the; cylindrical casing eoL timed so as to advance itor retard it. The :onstruction thus liar described Well known. Adjacen`its lowest point the 14 has a peripheral slot 1G.

The circuit breaker comprises a disk 17 a'iixed to the shaft 10 by abolt 18 and mounted to rotate Afreely in the casing 14. It bearsinsulation 19 on its face, and against this insulation is secured acontact piece 20. A screw 21 passes through the contact piece 2O andinsulation 19, and engages the disk 17 but the screw is insulated fromthe aperture through which it passes in the piece 20, and its head isseparated from the piece 2O by an insulating Washer 22. Also a lockWasher 23 may be added to keep the screw tight. In a projection 24 ofthe piece 20 is mounted an electro-de 25. The bolt 1S passes through theContact piece 2O and makes contact therewith. lt is insulated from thedisk 17 and the shaft 10, and connected at its inner end to one terminalof the generating Winding ol the magneto in the usual Way; the otherterminal of this winding being grounded. v On the disk 17 and inelectrical connection therewith is a pivoted lever 26, carrying` anelectrode 27 cooperating with the electrode 25. Then these electrodesare in contact the circuit is completed through the breaker lever 2G,the disk 17, t-he housing or framework of the magneto, the generatorWinding by Way or" its grounded terminal, the bolt or stem 13, contactpiece 20 and electrode 25. A spring,r 2S holds the lever 2G on itspivot; and the end opposite the electrode 27 bears a libre insert 30 tobe engaged by cam projections 31 and on the inside of the casing 14, tobe actuated thereby and thus separate the electrodes 25 and 27 when theinstant of ignition is reached. These cams may be integral with thecasing 14, or be made as internal projections on a. separate ring 33,indicated in broken lines in Fig. 2 attached to the inside of the casing14 and constituting with the cams and the casing 14 means ior ac`tuating the ,interruptein A spring 34 a'liixed to the disk 17 at asuitable point 35 and to the lever 26 holds the electrodes 25 and 27 inengagement. The parts of the circuit breaker are of the `usualconstruction and form no part of my invention.

Then the cam projections 31 and 32 ar set by the easing 14 to operatethe breaker lever 26 at the most advanced point for the spari, theelectrodesor contacts 25 and 27 Will separate at the instant when thearmature is passing through the position shown in Fig. 3. The directiono'l rotation is assumed to be clockwise When the armature is viewed fromthe end connected to the drive shaft; that is, counterclockvvise whenviewed as shown in Figs. 2 and 3. At the exact 1nom'ent of ignition, thetrailing edge 0ll the head 6 will be separated from the adjacent tip ofthe nearest polepiece 5 by a space equal to that between the points 36and 37' in Fig.

3; and the trailing edge of the head 7 will be separated from theadjacent tip of the other polepiece 5 by the same interval. rl`hisinterval has already been mentioned above as the edge distance; and whenthe ring 14 is turned to cause the cams 31 and 32 to open the armaturecircuit at the electrodes and 27 at any later point in the rotation ofthe armature, this edge dista-nce increased. 'lfhe point oi maximumadvance for the spark is lined by attaching to the end of' the housing 1belov.7 the casino' 14 an adjusting device 38; which has slots D in endsfor screws 40. The adjusting device is secured against the end oi thehousing 1 in transverse position, and it has a central projection 4l onits upper edge which enters the slot 16 and abuts against the end ofthis slot at the right, as appears in Figs. 2 and 3, whenA the casing 14is set to cause an advanced spark to be given by the circuit breaker.Hence, to set the circuit breaker at maximum advance position l'or thespark, one neet-.s only to turn the casing with the arm 15 till theright hand end of the slot 16 abuts the projection 4l.

However, variations are generally found when the magneto is assembled;and if the member 3S Were in absolutely fixed position, the edgedist-ance between the points 36 and might be either too large, or toosmall, When the circuit breaker is set for advanced sparking with theright hand end oi.l the slot 1G abutting the projection 41. Henceoliicient operation for this point could not be had, and the magnetowould also not per- Jform at its best for other positions of the casing14 and cams 31 and 32. Therefore the member 38 has its openings 39elongated so that it can be shifted. from one side of the magneto to theother. In Figs. 2, 3 and 4 these openings or slots lie on an areconcentric with the axis of rotation of the armature; and by theloosening of the screws 41, the device 3S can be adjusted so that theprojection 41 is caused to occupy a true position Wiich will enable thecasing 14, when. the right hand end of the slot 1G engages theprojection 41, to hold the cams 31 and 32 in place to enable the breakerlever to operate at the exact point to give the edge distance its propervalue.

In Fig. 5 the member 3S has slots 42 which are longitudinal, instead oillying on an are concentric with the axis oit' rotation of the armature.

The easing 14 has a cover 43, and to the end of the magneto is fixed apost 44, bear ing a pivoted spring` arm 46 to engage the cover and keepit in place. The arm is swung aside when the cover is to be removed. Asocket 47 on the disk 17 carries the usual carbon brush to engage theend of the magneto and insure ay goed ground connection for the disk .17and the contact 27.

71th the device 38 `the edge distance can lll) .- rendered unnecessary.

be set with the greatest ease and accuracy by simply loosening and thentightening the screws 40, after shifting the device 38 in the requiredmanner. y l

The member 38 as shown is plane or flat, and its ends with the slots 39are widened. In the middle, where it has the projection 41, it is narrowenough to clear the post 44, and its upper edge may be `concave andcurved to some extent `according to the curv-Y ature of the casing 14.When the slots 38 are straight and longitudinal as in Fig. 5, there willalways be space enough between the upper edge of the member 38 and thecasing 14 to allow adjusting movement of this member for the purposeabove set forth.

The end of the magneto shown in Fig. 1 is integral with the housing; butthe invention is just as well adapted for magnetos in which this end isseparate and held on by screws or the like fastening means. j

By the use of the adjustable stop plate 38,l the disasselnbling andrechecking of the magneto, as well as any filing of the slot 16, are hearmature edge distance is set accurately and the plate is. moved'on thetwo screws 40 until the tongue 41 is brought against the end ot the slot16 at the right in Figs. 2 and 3. The screws 40 are then tightened andthe plate 38 secured. Hence much time andv labor in finishing the maneto are saved. i

aving described `my invention, what I j claim is:

1. In a magneto, an interrupter, means for actuating the interrupter,and a plane member held against the end of the magneto and 5 extendingadjustably across said end, said member engaging'said means to x theedge distance of said magneto. v

2. In a magneto, an interrupter, means for actuating the interrupter,and a plane member adjustably secured to the end of the magneto andengaging said means to adjust the edge distance of the magneto.

3. In a magneto, a rotatable interrupter, means for actuating theinterruptor, a plane member disposed against the end of the magneto, aprojection on said member to engage said means, slots in said member,and means on the magneto passing through said slots for securing themember to the magneto and per` mitting movement of said member to ix theedge distance of the magneto. Y

4. The combination `according to claim 3 wherein the slots are straightand extend longitudinally of said member.

5. The combination according to claiml 3 wherein the slots are curvedand lie on'an arc concentric with the aXis of rotation of theinterrupter.

6. In a magneto, a member for adjusting the edge distance, said memberbeing plane or flat and having a projection on one edge.

7. In a magneto, a member for adjusting the edge ldistance of themagneto, said member having wide ends with slots therein, a narrowmid-portion between said ends, and a lateral projection at saidmid-portion.

8. In a magneto, a member for ad'usting the edge distance of themagneto, sai member having slotted ends and a concave edge,

with a projection on said edge.

9. In a magneto, an interrupter, a casing having means to actuate theinterrupter, the` magneto having a projecting end received in saidcasing to support the latter, the casing having a slot in its lowerside, a plane member secured at against said end below said casing intransverse position, said member having a pro ection to enter said slot,the ends of said mem er also having slots, and mea-ns passing throughsaid last named slots to hold the member adjustably against the`magneto. 10. In a magneto, an interrupter, a casing adjustably mountedon'the magneto to en` close the interrupter, a cover for the casing, apost attached to the magneto adjacent said casing, an arm on the post tohold the cover in place, and a device to fix the ed e distance of themagneto, adjustably attac ed to the magneto between said post and saidcasing.

11. The combination according to claim 10, wherein said vdevice haswidened endsgand a narrow portion in proximity to said post.

' 12. The combination according to claim l0, wherein said device has aprojection adjacent said post to engage the casing.

In testimony whereof I affix my Signature.

JOHN F. MARTIN.

